Malaria is a wide spread disease, particularly in the developing countries, and scientists are constantly looking for new means to control the dangerous parasitic disease caused by plasmodial parasites. Among these parasites Plasmodium falciparum causes the most severe disease, responsible for the major part of the mortality due to malaria.
One strategy in combatting malaria resides in the use of a conventional vaccine based on attenuated or dead malaria parasites, but such approach has not been found to be practically feasible.
The alternatives are constituted by development of modern techniques, such as the manufacture of proteins by chemical synthesis or by DNA technology, such proteins as components in subunit vaccines being able to induce protective immunity against the parasite infection.
One strategy in the selection of antigenic sequences to be included in a potential subunit vaccine against Plasmodium falciparum malaria is to define the epitopes of antibodies which have the capacity to interfere with the parasite life cycle. Properly presented in immunogens these epitopes are expected to induce protective antibody responses. With regard to the asexual blood-stages of P. falciparum, the main attention in this context has been made to antibodies with capacity to inhibit merozoite reinvasion in vitro (Anders, R. F. (1985) Candidate antigens for an asexual blood-stage vaccine. Parasitol. Today 1, 152-155). However, antibodies which inhibit the cytoadherence of infected erythrocytes to endothelial cells (Howard, R. J. (1988) Malarial proteins at the membrane of Plasmodium falciparum-infected erythrocytes and their involvement in cytoadherence to endothelial cells. Prog.Allergy 41, 98-147; Udomsangpetch, R., Aikawa, M., Berzins, K., Wahlgren, M. and Perlmann, P. (1989) Cytoadherence of knobless Plasmodium falciparum-infected erythrocytes and its inhibition by a human monoclonal antibody. Nature 338, 763-765) or inhibit rosette formation between uninfected and infected erythrocytes (Carlsson, J., Holmquist, G., Taylor, D. W., Perlmann, P. and Wahlgren, M. (1990) Antibodies to a histidine-rich protein (PfHRP1) disrupt spontaneously formed Plasmodium falciparum erythrocyte rosettes. Proc.Natl.Acad. Sci. USA 87, 2511-2515) may also be of interest. Such antibodies are expected to interfere in vivo with the sequestration of late-stage infected erythrocytes (Howard, R. J. (1988) Malarial proteins at the membrane of Plasmodium falciparum-infected erythrocytes and their involvement in cytoadherence to endothelial cells. Prog.Allergy 41, 98-147; Carlson, J., Holmquist, G., Taylor, D. W., Perlmann, P. and Wahlgren, M. (1990) Antibodies to a bistidine-rich protein (PfHRP1) disrupt spontaneously formed Plasmodium falciparum erythrocyte rosettes. Proc.Natl.Acad.Sci. USA 87, 2511-2515).
The human monoclonal antibody (mAb) 33G2, obtained from an Epstein-Barr virus transformed B-cell originating from a Liberian P.falciparum-immune donor (Udomsangpetch, R., Lundgren, K., Berzins, K., Wahlin, B., Perlmann, H., Troye-Blomberg, M., Carlsson, J., Wahlgren, M., Perlmann, P. and Bj orkman, A. (1986) Human monoclonal antibodies to Pf155, a major antigen of malaria parasite Plasmodium falciparum. Science 231, 57-59) has several interesting biological properties. It inhibits both P.falciparum merozoite reinvasion in in vitro cultures (Udomsangpetch, R., Lundgren, K., Berzins, K., W ahlin, B., Perlmann, H., Troye-Blomberg, M, Carlson, J., Wahlgren, M., Perlmann, P. and Bj orkman, A. (1986) Human monoclonal antibodies to Pf155, a major antigen of malaria parasite Plasmodium falciparum. Science 231, 57-59) as well as cytoadherence of infected erythrocytes to melanoma cells in vitro (Udomsangpetch, R., Aikawa, M., Berzins, K., Wahlgren, M. and Perlmann, P. (1989) Cytoadherence of knobless Plasmodium falciparum-infected erythrocytes and its inhibition by a human monoclonal antibody. Nature 338, 763-765). The mAb, thus, has the capacity to interfere with the parasite erythrocytic life cycle at two potential target sites for protective antibodies in vivo (Anders, R. F. (1985) Candidate artigens for an asexual blood-stage vaccine. Parasitol. Today 1, 152-155) which makes the epitope recognized by the mAb of great interest with regard to vaccine development.
The mAb 33G2 was initially selected due to its reactivity with Pf155/RESA as detected by erythrocyte membrane immunofluorescence (EMIF) and immunoblotting (Udomsangpetch, R., Lundgren, K., Berzins, K., W ahlin, B., Perlmann, H., Troye-Blomberg, M., Carlsson, J., Wahlgren, M., Perlmann, P. and Bj orkman, A. (1986) Human monoclonal antibodies to Pf155, a major antigen of malaria parasite Plasmodium falciparum. Science 231, 57-59) but subsequent analyses with recombinant fusion proteins and synthetic peptides revealed that the antibody showed reactivity with a family of cross-reacting P.falciparum blood-stage antigens, including Pf155/RESA, Pf11.1 and Ag332 (Mattei, D., Berzins, K., Wahlgren, M., Udomsangpetch, R., Perlmann, P., Griesser, H. W., Scherf, A., M uller-Hill, B., Bonnefoy, S., Guilotte, M., Langsley, G., Pereira da Silva, L. and Mercereau-Puijalon, O. (1989) Cross-reactive antigenic determinants present on different Plasmodium falciparum blood-stage antigens. Parasite Immunol. 11, 15-30; Mercereau-Puijalon, O., Langsley, G., Mattei, D., Guilotte, M., Blisnick, T., Berzins, K., Griesser, H. W., Scherf, A., M uller-Hill, B. and Pereira da Silva, L. (1987) Presence of cross-reacting determinants on several blood-stage antigens of Plasmodium falciparum. UCLA Symp.Molec. Cell.Biol. 42, 343354; Udomsangpetch, R., Carlsson, J., W ahlin, B., Holmquist, G., Ozaki, L. S., Scherf, A., Mattei, D., Mercereau-Puijalon, O., Uni, S., Aikawa, M., Perzins, K. and Perlmann, P. (1989) Reactivity of the human monoclonal antibody 33G2 with repeated sequences of three distinct Plasmodium falciparum antigens. J. Immunol. 142, 3620-3626). A feature shared between these antigens is their contents of several tandemly repeated amino acid sequences containing regularly spaced pairs of glutamic acid (Mattei, D., Berzins, K., Wahlgren, M., Udomsangpetch, R., Perlmann, P., Griesser, H. W., Scherf, A., M uller-Hill, B., Bonnefoy, S., Guillotte, M., Langsley, G., Pereira da Silva, L. and Mercereau-Puijalon, O. (1989) Cross-reactive antigenic determinants present on different Plasmodium falciparum blood-stage antigens. Parasite Immunol. 11, 15-30; Favaloro, J. M., Coppel, R. L., Corcoran, L. M., Foote, S. J., Brown, G. V., Anders, R. F. and Kemp, D. J. (1986) Structure of the RESA gene of Plasmodium falciparum. Nucleic Acids Res. 14, 8265-8277; Scherf, A., Hilbich, C., Sieg, K., Mattei, D., Mercereau-Puijalon, O. and M uller-Hill, B. (1988) The 11-1 gene of Plasmodium falciparum codes for distinct fast evolving repeats. EMBO J. 7, 1129-1137). These dimers of glutamic acid were suggested to be the structures responsible for the antigenic cross-reactions seen between the three antigens (Mattei, D., Berzins, K., Wahlgren, M., Udomsangpetch, R., Perlmann, P., Griesser, H. W., Scherf, A., M uller-Hill, B., Bonnefoy, S., Guilotte, M., Langsley, G., Pereira da Silva, L. and Mercereau-Puijalon, O. (1989) Cross-reactive antigenic determinants present on different Plasmodium falciparum blood-stage antigens. Parasite Immunol. 11, 15-30; Merecereau-Puijalon, O., Langsley, G., Mattei, D., Guilotte, M., Blisnick, T., Berzins, K., Griesser, H. W., Scherf, A., M uller-Hill, B. and Pereira da Silva, L. (1987) Presence of cross-reacting determinants on several blood-stage antigens of Plasmodium falciparum. UCLA Symp.Molec. Cell.Biol. 42, 343-354; Udomsangpetch, R., Carlsson, J., W ahlin, B., Holmquist, G., Ozaki, L. S., Scherf, A., Mattei, D., Mercereau-Puijalon, O., Uni, S., Aikawa, M., Berzins, K. and Perlmann, P. (1989) Reactivity of the human monoclonal antibody 33G2 with repeated sequences of three distinct Plasmodium falciparum antigens. J. Immunol. 142, 3620-3626). Inhibition with synthetic peptides of the mAb 33G2 binding in EMIF showed that peptides corresponding to Ag332 repeat sequences were the most efficient inhibitors, suggesting that Ag332 was the original target for the antibody (Udomsangpetch, R., Carlsson, J., W ahlin, B., Holmquist, G., Ozaki, L. S., Scharf, A., Mattei, D., Mercereau-Puijalon, O., Uni, S., Aikawa, M., Berzins, K. and Perlmann, P. (1989) Reactivity of the human monoclonal antibody 33G2 with repeated sequences of three distinct Plasmodium falciparum antigens. J. Immunol. 142, 3620-3626).
The major object of the present invention is to provide new peptides capable of inducing immunity against malaria.
Another object of the invention is to provide new compositions for vaccination against malaria comprising such peptide.
Yet another object of the invention is to provide a method of inducing immunity against malaria.